Strand handling apparatus



March 16, 1943. c. c. SMITH 2,

STRAND HANDLING APPARATUS Filed July 31:1941

a/ a2 F! a. I T T FIG. 6

INVENTOP C. 6. SMITH Patented Mar. 16, 1943 2,314,168 STRAND HANDLINGAPPARATUS Charles C. Smith, Cranford, N. L, assignor to Western ElectricCompany, Incorporated, New

York, N. Y.,

a corporation of New York Application July 31, 1941, Serial No. 404,8924 Claims. (Cl. 91-53) This invention relates to strand handlingapparatus, and more particularly to apparatus for coating strands.

Insulating sheathings on electrical conductors are made, at the presenttime, in a multitude of ways, some of which include the application to abare or previously variously sheathed strand of hardenable materialsapplied in liquid, semiliquid, or pasty form and subsequently hardened.Thus materials in the nature of paint, enamel, varnish, or waxes,asphalts, parafiins and the like dissolved in volatile vehicles,artificial resins hardenable by polymerization induced by heat, andother analogous materials are used for one or another specific purpose.In many such instances a solvent or vehicle is used which is volatilizedto be subsequently recovered; and a considerable part of the cost of thecoating operation may arise out of the volume of such solvent or vehicleto be recovered for subsequent reuse. Hence it is desirable and may bevitally important to apply the raw sheathing or sheath treatingmaterials in a condition approaching dryness as nearly as may bepracticable, i. e. as a smoothly plastic highly viscous paste, in orderthat the volume of vehicle or solvent circulated in the process, orperhaps wasted, may be kept low.

An object of the present invention is to provide simple, reliable andeasily interchangeable means for applying to strands of a considerablerange of diameters, material whose physical state is that of a smoothlyplastic but highly viscous and thick paste to form a uniform coating onthe strands.

With the above and other objects in view, the invention may be embodiedby providing in an apparatus having means to apply coating material to astrand and including a chambered body to contain the material and formedwith entrance and exit apertures to pass a strand to be coated throughthe material, means to wipe the strand comprising a plug of elasticmaterial having a bore therethrough of approximately the diameter of thestrand, and means to support the plug in the exit aperture of the body,the plug being further formed to have a free surface running in the samegeneral direction as the bore to provide room for dilation of the boreupon the passing therelthrough of a swollen portion of the strand.

Other features and objects of the invention will appear from thefollowing detailed description of one embodiment of the invention takenin connection with the accompanying drawing'in which the same referencenumerals are applied to identical parts in the several figures and inwhich Fig. 1 is a view in vertical transverse central section of anapparatus for coating strands and constructed in accordance with theinvention;

Fig. 2 is a central section on an enlarged scale of the wiper plugs ofFig. 1;

Fig. 3 is a plan view of the plug of Fig. 2;

Fig. 4 is a view similar to Fig. 2 of a modified form of plug;

Fig. 5 is a plan view of the plug of Fig. 4;

Fig. 6 is a view similar to Fig. 4 of another form of plug; and

Fig. 7 is a plan view thereof.

As herein shown the invention is illustrated as embodied in a device forapplying a smooth, even, continuous coating of smoothly plastic, highlyviscous, thick, pasty material on a strand passed through the device.The device comprises a metal body IE] of generally parallelopipedalouter form having a cylindrical chamber ll axially therein and enclosedlaterally and at one end by the body but opening at l2 through the otherend and through a conical nipple l3 integral with the body. Four radialbores in diametral pairs M, I5 and l6, l1 respectively communicate fromthe chamber ll out through opposite sidewalls of the body.

A metal supporting cup [8, flanged to be supported on the outer surfaceof the body I0, fits tightly in the bore l4 and contains and supports ashort cylindrical sealing plug IQ of soft vulcanized rubber having anaxial bore 20. The plug I9 fits tightly into the cup and is supported onits inner face by the bottom of the cup which has a central, tapered,radially inwardly widening aperture 2| coaxial with the bore 20 of theplug. On the outward face of the plug l9 rests the broad flange of acoaxial tubular lead in guide 22, which in turn is held in place by acentrally bored nut 23 screwed into (the outer end of the cup I8.

In the diametrally opposite bore i5 is a metal sleeve 24 flanged to besupported on the outer face of the body l0 and having a radiallyinwardly narrowing, tapered bore in which is seated a correspondinglydimensioned, conically tapering wiping die or plug 40 of soft vulcanizedrubber. A cap 25 of metal is seated in a counterbore in the outer end ofthe sleeve and supports the plug 40 against outward movement. The cap 25is further formed with a central aperture 26 coaxial with an axial bore4| in the plug, A

sleeve 21 and cap 28, duplicates of the sleeve 24 and cap 25, arepositioned in the bore I I and hold in place a rubber plug 50 identicalin form with the plug 45. A cup 29 analogous to the cup I 8 but having aconical recess instead of a cylindrical one is mounted in the bore l5and has a cap 30 identically like the caps 25 and 28. The caps 25 and28, and thereby the sleeves 24 and 21, are held in place by a suitableyoke 3| held in place on the body by a screw 32. The cap 30 and therebythe cup 29 are held in place by a yoke 33 which also holds the cup |8 inplace and is held by a screw 34. A soft rubber plug 60, identically likethe plugs 40 and 50, is seated in the cup 29.

Turning now to Figs. 2 and 3, the plug 40 is a frusto-conical body ofsoft vulcanized rubber with parallel end faces. It is formed with theaxial, cylindrical bore 4|. As oriented in Fig. 2, there is also arecess 42, 43 opening upwardly from the bottom (smaller) end face 45.This recess or groove has an inner cylindrical wall 43 coaxial with thebore 4|, and an outer slightly conical wall 42 also coaxial with thebore 4| and therefore with the wall 43. At something more than half theheight of the plug above the bottom the walls 42 and 43 are joined andthe recess closed by a short cross wall 44.

It is found that, for optimum operation as hereinafter described, thediameter of the inner wall 43 should be about of the diameter of thebottom face 45; the recess should be about as deep as the plug is h ghand the width of the recess at its opening should be about of thediameter of the face 45. The relative width of the top face 45 and theslope of the conical outer face 41 are not materially important. Thediameter of the top face 40 as shown is about of the diameter of thebottom face 45. The height of the plug between the faces 45 and 45should be about the same as the diameter of the wall 43, i. e. about ofthe diameter of the face 45. Furthermore, the diameter of the hole 25 inthe cap 25 which supports the plug 40, should be about of the diameterof the face 45 or about A of the diameter of thewall 43. These optimumvalues have been determined in connection with the specific case ofoperation described below in which a strand of 22 gauge (A. W. G.)tinned and enamelled wire with three served layers of textile threads onit and having an average overall diameter of 0.047 inch, is to be coatedwith two consecutive layers of a thick, highly viscous, smoothly plasticpaste comprising cellulose acetate softened with acetone. Thedimensional ratios given above are not acutely critical and in othercases may well be somewhat modified without harm to the results desired;but, generally speaking they appear to be optimum values.

The coating of strands with such materials as are here in questionpresents difficulties as well as advantages not known in the earlierart. A typical materialv heretofore in use contains about 20% of solids,largely cellulose acetate, in about 80% of solvent, largely acetone.Such a preparation is a sirupy but definitely fluid liquid, can bepoured, and will flow through apipe under gravity alone. Its viscositywillbe around 2000 poises or less at 105 F.

As already pointed out it is the particular purpose of the presentinvention to create a strand having a coating of thick. pastily almostsolid, viscous material ordinarily five or six times as thick as thatwhich can be created on a strand in the case of the relatively thinSirupy,

raw coating materials heretofore used. This is highly advantageous,because the number of coating passes of the strand and therefore of theensuing hardening passes is cut to one-fifth or one-sixth in number ofthose heretofore required to produce coats of like final thickness; alsobecause the volume of solvent required to be evaporated off and eitherwasted or expensively recovered is very materially diminished, so muchso that it may well be cheaper to waste the evaporated solvent than tomaintain and operate the expensive recovery plant previously necessary.

In one instance a coating material was used. typical in physicalcharacteristics of materials adapted for the present invention, whichcontained' 58% by weight of solids (largely cellulose acetate) and 42%by weight of a liquid vehicle containing, in 42 parts, 40 parts ofacetone and 2 parts of other liquids. The viscosity of this was about25,000 poises at 75 F. and at the extrusion temperature of about F. itwas about 18,000 poises. It could not be poured or transferred in themanner of ordinary liquids except under pressure. In one instance inpractise, it required a ressure of lbs. per square inch to transfer theabove mixture through a pipe.

In using the device hereinabove described for coating a strand such asthe 0.047 inch diameter, textile thread served, No. 22 wire abovementioned with the pasty preparation of cellulose acetate describedabove, a wire 35 such as described, drawn from some suitable supplybelow (Fig. 1), is threaded through the tubular guide 22 and the rubberseal IS, the bore 20 of which is of about the same diameter as the wireor minutely larger, say in the particular instance under considerationfrom 0.047 to 0.050 inch. The wire is led across the chamber H and outthrough the bore 4| of the plug 40 and the aperture 26 of the cap 25.Thence the wire passes through suitable means to partially or whollyharden the coating, which means are not shown as they form no part ofthe present invention. Thence the once coated wire returns to passupwardly again through the plug 60, the chamber H and the plug 50 toenter the hardenmg means again.

The Wire having been threaded in this fashion, the nipple i3 at theentrance I2 is connected to some suitable source (not shown) of thepasty cellulose acetate material under pressure which fills the chamberII, the contained air be ng forced out the bores of the several plugs.When the chamber is filled with paste under pressure (about 90 poundsper square inch in. the particular instance illustrated), the wire isadvanced by any suitable means (not shown) in the direction indicated bythe arrows. The bore 4| and the corresponding bore 5| in the plug 50 areof approximately the average diameter of the strand 9. The paste underpressure clings to the strand and is wiped off by the Wiping dies 40 and55, leaving a coating of suitable thickness on the wire emerging fromthe dies, the thickness being controlled by the size of the bores 4| and5|, bythe hardness of the rubber plugs 40 and 5|) and bythe pressure inthe charm ber Plugs 40 and 50 having the dimension ratios indicated anda bore of about 0.048 inch anda 50-60 durometer hardness aresatisfactory for the particular wire in question.

In practise there will inevitably be irregularities in diameter of thewire. Perhapsthe most frequent cause of such are splices in the wirewhere ends have been joined together by welding. Or there may be knotsin textile threads served on the wire core. A plug 40 must necessarilybe temporarily and locally distorted when a knot, weld or other swellingof the strand passes through it. Rubber is elastically and easilydistortable, as is well known. However, it is not always realized thatrubber is much like a liquid in that it is nearly incompressiblevolumetrically. If a mass of soft rubber is to be shortened by pressurein one direction, it must be free to expand in some other direction.

In the present instance, when a knot enters the bottom of the bore 4|and moves upwardly in it, the rubber of the stem-like part within thewall 43 is free to expand into the annular recess 42, 43. When the knotis at the level of the end 44 of the recess, the rubber in front of it(above) can swell out into the opening 26 of the cap 25, M

which opening is about two and one-half times the diameter of the bore4|. Thus every part of the rubber stressed by the dilation of the boreby the passage of a swelling in the strand is free to yield in somedirection with substantially con?- stant resistance, for every part ofthe bore 4| is at substantially the same distance from some free surfaceof the plug, except of course theentrancje and exit parts which arenearer. But no part is farther from a free surface than the middle p01tion of the bore is from the surface 43. Hence a swelling on the strandmay pass through the bore without undue resistance at any point. Werethe recess 42, 43 not there, all the substance of the plug would becontained within rigidly confined faces except the small portion nearthe exit of the bore. That the rear face 45 is free is immaterialbecause all the stress occasioned by a knot passing in the directionindicated is toward the walls 46 and 41. Hence with an unrecessed plug,the resistance to passage of a knot rises abruptly and severely shortlyafter the knot enters the bore.

A less satisfactory but still sometimes practicable way of accomplishingthe same result is shown in Figs. 4 and 5. Here a plug I40 isidentically like the plug 40 in general dimensions, in mode of use andin the diameter of the bore 4|. There is, however, no annular recess.Instead a segment is cut away at one side along a vertical plane,leaving the flat surface I48. Thus the material around the bore 4| hasthe free surface I48 to move toward when a knot goes erally in which thedevices herein described may be found, such may befound in copendingapplication Serial No. 382,726 filed March 11, 1941,

5 by E. E. Newton et a1. and assigned to the same assignee as thepresent application.

The embodiments of the present invention herein disclosed areillustrative and may be variously modified and departed from withoutdeparting from the spirit and scope of the invention as pointed out inand limited only by the appended claims.

What is claimed is:

1. A strand wiping die of elastically deformable material having aboretherethrough and formed with a recess having a free surface runningin the same general direction as the bore to provide room for dilationof the bore upon the passing therethrough of a swollen portion of thestrand.

2. A strand wiping die of elastically deformable material having a boretherethrough and formed with a curved recess coaxial with the bore andhaving a free surface running in the same general direction as the boreto provide room for dilation of the bore upon the passing therethroughof a swollen portion of the strand.

3. A strand wiping die of elastically deformable material having a boretherethrough and formed with an annular recess coaxial with the bore andhaving a free surface running in the same general direction as the boreto provide room for dilation of the bore upon the passing therethroughof a swollen portion of the strand.

4. A strand wiping die of elastically deformable material having a boretherethrough and formed with arecess in a side wall thereof having afree surface running in the same general direction as the bore toprovide room for dilation of the bore upon the passing therethrough of aswollen portion of the strand.

CHARLES C. SMITH.

